Print Page | Close Window

New Member/Old Topic

Printed From: Graham Slee Hifi System Components
Category: Find what you're looking for here!
Forum Name: New Members Corner
Forum Description: Introduce yourself here
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=4673
Printed Date: 29 Mar 2024 at 10:29am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: New Member/Old Topic
Posted By: DogBox
Subject: New Member/Old Topic
Date Posted: 27 Feb 2019 at 10:46pm
Hello all! 
And ThankYou! for the chance to possibly add a little, from a different view[point]! 
I have been going through a bit of "six degree's of separation" all because of the Ceramic Cartridge that Mr Slee found and put it up against the idea of RIAA/Magnetic use of Cartridges giving us a platform that we are happy enough to walk on until someone comes and resurfaces the platform with carpet! Well, almost! 
I read with amazement the Forum Topic: questioning-phono-sanity_topic1370_ where the Sonotone 9TA[HC or not] was found to give a wonderful account of itself. I first came across this cartridge when I had to do repairs to an old Kriesler Model 11-95 that has a Garrard Type AT6 Turntable, 9TA SD Diamond Stylus. Going on UK ebay where the best Turntable Spares are found [I think..?] I was surprised to find this Cartridge, New! and in quantity! Degree 2! Being interested in HiFi, Turntables [which I try and do repairs on and get new Stylus for] and having made the Moving Coil version of the Silicon Chip Phono Preamp; I was ecstatic to find that Mr Graham Slee [famous in my books!] had a Kit I could make! Then doing a further search on the Customers Kriesler, I find myself back on this website on the subject of the 9TA! Click in another degree! 
 Remembering I had an old Valve Book that had Schematics in the back, I would like to ask Mr Slee if he had seen the "PREAMPLIFIER FOR CERAMIC PHONOGRAPH PICKUP" schematic in the RCA RECEIVING TUBE MANUAL? It uses a single 6J7 valve in a Cathode-Follower (Low Impedance) Output design. 
 Seeing that I have come to the bottom of my writing space, I will leave it there for now, being a very happy chappy to be able to make a contribution, hopefully of some worth! Wink
Kind Regards,
DogBox [Steve]    



Replies:
Posted By: Graham Slee
Date Posted: 28 Feb 2019 at 7:31am
Hi Steve, welcome (and by the way the box expands to fit your writing so please keep going).

I'm taking a wild guess here, but I think you may be upset with me because you expected to see a circuit/product that would preamp the 9TA?

I can put that right. And even before I get in drawing mode I can point you at this magazine: https://www.americanradiohistory.com/Archive-Practical/Wireless/70s/PW-1976-07.pdf - https://www.americanradiohistory.com/Archive-Practical/Wireless/70s/PW-1976-07.pdf - you need page 229 (39 in your browser page counter).

It should cost less than £10 in parts, and can be easily modified to work on two E-cell 9 volt batteries wired in series. Just remove R17 (15k resistor) and take the positive supply to R13-C9 junction. Making C9 100uF will improve matters using a battery supply.

The components are numbered such that it makes 4 channels which is 2 stereo channels because it was intended for a twin-deck. Obviously you only need 2 channels. C5 isn't really required as the cartridge itself blocks DC because it is the equivalent of a 600pF capacitor. C1 should be better than a ceramic, and a 47pF polystyrene should be more suited. The BC184 transistor (as well as all the other bits) is available from Rapid Electronics, but I used a BC109.

I built this in July 1976 after constructing the PW Easy-build Disco, and it sounded good to me at the time (aged 21).


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 28 Feb 2019 at 10:15am
...I think you may be upset with me.." who me? LOL No way! 
I was just wondering if you had seen the RCA schematic and 'their take' on a preamp using a valve? 
Was going to try and upload it if you wanted/thought worth it? 
 I am definately not clever enough to be even get a 'bit miffed' - maybe envious at your talent - but have no reason to be angry.. 
 Actually, thinking about how the industry went about recording, I seem to remember learning from that silicon chip build that Decca had their "ffss" Full Frequency Stereophonic Sound that they cut their records to, so you had to alter the RIAA filtering to suit. I found your article really interesting and was waiting for your take on promoting Ceramic Cartridges - even suggesting a design and a preamp to go with it that would revolutionize our record playing experience! I saw you make a prototype preamp.. didn't it inspire you enough to 'run with it a little more..?' I think the question still remains: Is "magnetism" the "best driving force" for vinyl replay..? Is there No Other method for generating a voltage from the patterning groove laid down by the cutting lathe of sound recording...? MM & MC both use magnets. Isn't the Ceramic Pickup able to do "just as good a job" of sound retrival? if not "cleaner" by not having magnets to assist and skewing frequency..? 
 Thankyou! so much for your warm welcome and I think you would make a great electronics teacher! I've already learnt a heap! Now i'll go and check out that magazine you suggested. Thanks! 
Kind Regards,
DogBox   


Posted By: Graham Slee
Date Posted: 28 Feb 2019 at 10:04pm
Originally posted by DogBox DogBox wrote:

...just wondering if you had seen the RCA schematic and 'their take' on a preamp using a valve?


I think I may have that in one of my books: "The preamplifier uses a 7199 triode-pentode in a high-gain pentode input stage..."? If not that one I'd be interested in seeing it.

Originally posted by DogBox DogBox wrote:

I seem to remember learning from that silicon chip build that Decca had their "ffss" Full Frequency Stereophonic Sound that they cut their records to, so you had to alter the RIAA filtering to suit.


Perhaps they meant FFRR? It preceded RIAA and had an upper time constant of 50uS so RIAA (75uS) makes it sound a little dull.

Originally posted by DogBox DogBox wrote:

I found your article really interesting and was waiting for your take on promoting Ceramic Cartridges - even suggesting a design and a preamp to go with it that would revolutionize our record playing experience! I saw you make a prototype preamp.. Didn’t it inspire you enough to 'run with it a little more..?' I think the question still remains: Is "magnetism" the "best driving force" for vinyl replay..? Is there No Other method for generating a voltage from the patterning groove laid down by the cutting lathe of sound recording...? MM & MC both use magnets. Isn't the Ceramic Pickup able to do "just as good a job" of sound retrieval? if not "cleaner" by not having magnets to assist and skewing frequency..?


What could have driven me on to 'run with it' would have been interest from a cartridge manufacturer (third party OEM, that sort of thing). I tried a contact or two but they thought it a crazy idea. But with some modern engineering of the type that goes into MMs or MCs; some good suspension and some better piezo material, it could use a modern type diamond stylus, and might perform as good.

A ceramic gives higher output and best of all, it's flat, whereas a magnetic has a rising response (constant velocity), and would only need the record's own EQ. Instead, with magnetics we have all kinds of noise and gain problems to overcome, as well as EQ'ing the cartridge.

To try and keep up with sales, Sonotone started making ceramics with a built in equaliser to make them output the same as a MM, which basically meant making matters worse. It died. (http://www.roger-russell.com/sonopg/sonopc.htm)

In the end I decided to turn the tables (pun unintended) and put a magnetic equaliser on the front end of a ceramic EQ stage, applied for a patent (and got it), and called it an Accession.

Originally posted by DogBox DogBox wrote:

I think you would make a great electronics teacher! I've already learnt a heap!

I'm far too unorganized for that, although it isn't the first time somebody suggested it. But I'm well past teacher retirement age, and sometimes I have to look-up things I should be able to remember Embarrassed



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 28 Feb 2019 at 11:01pm
Graham said:think I may have that in one of my books: "The preamplifier uses a 7199 triode-pentode in a high-gain pentode input stage..."? If not that one I'd be interested in seeing it. 
Tried to upload but my dinosaur vista operated thingy-majig will only do PDF Confused Cry 
 However, it uses a 6J7 in a Cathode-Follower Output. The 6J7 is a "Sharp Cut-Off Pentode" which can also be used in a Triode Connection. 
The schematic shows an AF output of 50kOhms..?? Which from previous readings seems high..??? 
 I sent the schematic by email and hope you may be able to help everyone else to see the diagram? 
Also, haven't met a Teacher that had a perfect memory yet! Wink So You'll do fine! 
Kind Regards,
DogBox [Steve] 



Posted By: Graham Slee
Date Posted: 01 Mar 2019 at 9:01am
Thanks. Got it, and here it is:

Preamplifier for Ceramic Pick Up Cartridge


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Graham Slee
Date Posted: 01 Mar 2019 at 10:08am
As you can see, it's a cathode follower... Confused

Funny, isn't that thing at the top the plate or anode? And a 10n cap connects it to the output? A 50k load? Bass cut from 318 Hz! Yuk!

So where does the cathode go? To the suppresser grid, and via C1 to the screen grid, which is connected via R3 to HT.

So I think we can agree it isn't a cathode follower?



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Dave Friday
Date Posted: 01 Mar 2019 at 11:08am
And it isn't strapped as a triode!

-------------
lp12,oc9mk3,ca610p,krimson40watt pa,kef105.4


Posted By: DogBox
Date Posted: 02 Mar 2019 at 10:59am
Graham said:"So I think we can agree it isn't a cathode follower?" and 
Dave said: "And it isn't strapped as a triode!" 
So, Steve thought... "Can the RCA Manual be wrong...?" What if you replaced the 6J7 with a BC184 transistor..? And fixed up a few other things (?) Could it [even remotely!] be some sort of a simple Ceramic Phono Preamp? 
I really should study this. Basic transistor amplifier. Aren't "transistor-type" Phono Preamp's the best sounding? So, why is it so popular to 'use' 'Op Amps' when, with a little extra doings, you could have a superior unit? Or, are they "just" so noisy...?! 
Might have to ask our illustrious Master Slee... Thumbs Up 

Kind Regards,
DogBox [Steve] 


Posted By: Graham Slee
Date Posted: 02 Mar 2019 at 7:19pm
Illustrious?

If you're interested in making a transistorised phono preamp you can read about the pitfalls at the Doug Self Institute, and on Rod Elliott's website. Both consider op-amps to be superior, and they could be right.

http://www.douglas-self.com/ampins/discrete/2Q-RIAA/2Q-RIAA.htm - http://www.douglas-self.com/ampins/discrete/2Q-RIAA/2Q-RIAA.htm
http://sound.whsites.net/no-opamps.htm - http://sound.whsites.net/no-opamps.htm

I've made numerous transistor phono stages (amongst other transistor amplifier stages) and op-amps are much easier for the DIY'er to understand. I'd better not say that all the work's been done for you in an op-amp, because it hasn't, but most beginners can get some sort of performance out of an op-amp circuit with minimal understanding.

Getting them (op amps) to outperform the esoteric and often expensive stuff is a different matter. Then again, some of the expensive stuff is simply that: expensive, period.

My long-winded 70s Design Indulgence topic will eventually get back to the subject of a transistor phono stage, which is part of the transistor only concept of which I'm trying to achieve (a transistor integrated with offshoots).

The negative thing about op-amps is that you're stuck with the characteristics of the op-amp you choose. You don't have much control of the outcome. But often, to achieve the same measured spec using transistors, you end up with a discrete version of what's in an op-amp. Then why bother? Just use an op-amp to start with.

Op-amps have these characteristics (or signatures) because of how they were designed, and why they were designed as they were. For example the NE5534 and its offshoots. It was designed by Philips 40 years ago. It was a miracle of its time. It is signatured because of the way in which it was conceived: to follow audio thinking at that time. It was easy enough to make it have a complimentary output stage, but it's quazi-complimentary complete with Baxendall diode. I could go on about it but I'll save it for another topic.

I'll end up by saying that if a job's worth doing it's worth doing right. Watch the 1970s Design Indulgence topic to learn about the finer points using transistors.


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 07 Mar 2019 at 9:56pm
Originally posted by Graham Slee Graham Slee wrote:

Illustrious?

Getting them (op amps) to outperform the esoteric and often expensive stuff is a different matter. 

Ok, so what are we talking about "esoteric" and "expensive"? 
I went looking on the Texas site and found - only surface mounted, mind you! - a chip with 8 legs for $(US?)46.00...? an OPA??? of sorts..  

My long-winded 70s Design Indulgence topic will eventually get back to the subject of a transistor phono stage,.... 

I wait with baited breath! 

The negative thing about op-amps is that you're stuck with the characteristics of the op-amp.. You don't have much control of the outcome.... 

I thought that once you had found a Low Noise chip op-amp with a High Slew Rate, you could pretty-well pack everything around it to get the result you're after? Apparently no... Ouch

 Watch the 1970s Design Indulgence topic to learn about the finer points using transistors.
 
Since it's been a little while, I probably have catch-up to do...Embarrassed Forever grateful for all the patient teaching! StarClapClap


Posted By: Graham Slee
Date Posted: 08 Mar 2019 at 9:05am
You can't blame TI cashing-in on the mania. The gravy train holds vast fortunes for those who kissed the blarney stone. Unfortunately my Irish great grandmother's contribution to my DNA didn't contain that skill Wink

Op amps can be designed by an individual, or they might be designed by committee (a bit like the saying "a donkey is a racehorse designed by committee"), and I very much doubt anybody takes a good year over its discrete development, listening to a pile of records/flacs at each turn, prior to its large scale integration...

Wireless World served as an outlet for a number of talented designers to show off their design prowess, but we can also see their mistakes as we try and progress. As a consequence the NE553X includes a few of these - sounds great until it's been on a few days, when unless the designer compensates for its idiosyncrasies, it takes on a very dry and boring musical presentation.

Dogma can be false sometimes, and we run the risk of our eyes trying to cheat our ears. We are given 5 senses which are of equal importance, so why do we try and tell our hearing something is right just because our eyes saw it?



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 10 Mar 2019 at 11:59pm
Unfortunately my Irish great grandmother's contribution to my DNA didn't contain that.... 

But you 'have developed' a "skill" that hard work and a penchant for the truth as close as you can get it of understanding and designing "pleasure to your [and our!] ears!" 

Unfortunately, as you've said, sort-of, that when a "committee.." go about designing anything - money - is usually the main motive. Sad that money - more than ever, is still driving the world's rotation.. 
At least we get more pleasure and fun out of a belt to turn our's! 

I did see your encouragement to one member desiring of more knowledge, advising The Art Of Electronics... Upon my search to acquire that textbook; the price had me stopped in my tracks and to see if there was something else on the subject a little friendlier to the back pocket... I ummed and erred and decided on Electronics for Vinyl by Douglas Self. I'll get the other one next... Just hoping I have enough [never enough!] upstairs to make proper sense of it all! I'll probably need The Art of... to make sense of Elect for Vinyl! There is never a short cut to understanding... 
 I also went on the search for LF356 chips which don't seem as plentiful as I thought... Looking at the best offerings from TI: LME49710 & LM4562 are their top offerings..(?) I had it suggested to me that instead of the LF356 to opt for the OPA602AP with much faster slew rate?? 
 I'm sure those pieces have come before you prior to now and you can't wait to tell me how rubbish/committee designed they are! 
 I'm all ear's..! 

DogBox [Steve] 


Posted By: Graham Slee
Date Posted: 11 Mar 2019 at 10:05am
They say there is no correlation between wide-flat open-loop bandwidth and sound quality...

I liken it to Dorothy's black and white dream from the Wizard of Oz, and at the end of the film the charlatan pulling the levers (strings) is revealed (by a dog).

No correlation at all if you use 1920's test methods. We still rely on Harold Black. The baby-boomers generation onwards sit on their brains: stagnation.

Valve enthusiasts are hearing what wide-flat open-loop bandwidth does for sound quality, yet they'll buy the opposite for a preamp stage or headphone amp. Actually it's distortion most of them like.

Sorry Walt Jung, you, like me are wrong. Bob Pease, Doug Self, Bob Cordell (etc) are obviously right (based on 1920s discoveries). Otherwise I have much respect for Doug Self and perhaps a bit more for Bob Cordell, because he believes in emitter degeneration.

The Art of Electronics explains things from an independent position. It helps if you know how to make a basic transistor preamp to start with then everything else falls into place. You read textbooks via the index, to find what you need, and to find everything you need. It's not cover to cover (as I hope you know).

Seek and ye shall find... It's a sod for people like me who bought the books at such high prices, but most of them can be found as PDFs if you search long and hard (or even by accident).

The good sounding op-amps are being replaced by forced slew rate op-amps (or enhanced slew rate as the manufacturers prefer to call them). The bandwidth starts top-left at some ridiculous high gain, and rolls off to "light" on a constant -20dB per decade. Negative feedback is always 270 degrees at all frequencies, and not 180 degrees as it should be in our hearings range (just my opinion - and Walt Jung’s).

Input slew rate is natural slew rate, and JFET inputs or degenerated BJT inputs do that, but in doing so gain is the cost. That's no good in the op-amp market where gain is everything (high gain with NFB gives disappearingly low distortion). So it's forced at the output by feed forward techniques, cutting phase and gain margin to the minimum, often stating a minimum gain for stability. Such circuits can sound good at first, until they're burned-in. Always switch off as soon as you can...


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 11 Mar 2019 at 11:11am
Wot? Emitter degeneration.. ? Is that a happening thang going on inside the LME's and the OPA's or something inherent in BJT's I wonder..? Interesting concept! I finally got to read the http://www.douglas-self.com/ampins/discrete/2Q-RIAA/2Q-RIAA.htm page right through + the other sites/articles he referred to. Wonderfully interesting [headache forming] stuff that, I started to see what he was on about! The article he referred to - the link didn't work -  http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1965/Transistor%20High%20Quality%20Audio%20Amplifier.pdf is a brilliant read I didn't have enough time for, for it to add its bit to the story. Talk about looking at the contents to see what you need... follow the links keeps you in reading material for ages!... Also, another article from the Bibleography (?)  https://www.stereophile.com/features/cut_and_thrust_riaa_lp_equalization/index.html Pages 1,2,3,and The Neumann 4th pole (sic) - after pages 1&2 I ran out of time and my duties of looking after my mum take precedence... ah well, I needed a break! 
There's another guy I was waiting for on your list of 'Who got it right..' was Mr Pass.. or didn't he? 
Nelson seems so switched on it would be a real buzz to watch one of his seminars... shame I don't have the intelligence to grasp a lot of what he says - even if he does keep it pretty simple! 
 I am determined to read all of the 45 or so pages of the forum/phono-preamp-project_topic745.html and see if THAT won't teach me a thing or two! I figure, something like that has got to be worth a heck of a lot where you get the results along the way down the yellow brick road and the best explanation of why the bricks are arranged the way they are! Extremely valuable in my book! Something you just don't normally get - unless your Dad was an electronics technician, starting in the PMG (Australian Post Master General that looked after the phones in those days where you could also learn about electronics and he also got his Amateur Ham Radio Licence - built his own tube transceiver, learnt Black & White TV which he ended up selling and servicing,...) I just wasn't clever enough as a young fellow to know how wonderful it all was! Until I became interested in radio comms... my real start into electronics! Then dad died so I couldn't ask the questions I needed answers to for my learning to make sense. Thank goodness for Google! 
Now, a question that occurred the other day when you were talking about NFB... Can it be amplified along the way so that you can have the level you need to really be beneficial? I mean, once you create it in circuit,.. can't you then amplify it or increase its gain level to a point where it will then be beneficial? to the circuit? See, i'm showing my ignorance again and asking questions like this would drive my dad nuts! 
 Oh well, one day... Looking forward to my Genera Kit arriving so I can let IT burn in...slowly...!Thumbs Up 
Kind Regards,
DogBox [steve]   



Posted By: Graham Slee
Date Posted: 11 Mar 2019 at 8:10pm
Know how to read bode plots?

LF356: 75 degrees phase margin and better than 30dB gain margin.

OPA602: 22 degrees phase margin and they don't (daren't?) extend the graph below zero crossing so we have to guess gain margin (it won't be much).

My own thoughts are that people like the brightness of instability. I'd prefer a treble control to boost treble if I wanted brightness. The trouble is semantics: hi-fi isn't high fidelity anymore, but a majority will search "hi-fi" when looking for high fidelity (so we call ourselves HiFi System Components Ltd...)

The LF356 is not without problems though. It has an asymmetrical slew rate which isn't good for driving RIAA or tape head preamps using NFB EQ. And is why I never ventured further with it in the Genera.

The LF351 is better in that respect, and can beat the pants off these newbies. But they've made it difficult for the DIY'er to use by making it surface mount.

The LME49710 is "so superior" it doesn't need to show a bode plot. In my book that's arrogance, and close to subterfuge.

The LM4562 bode plot shows manipulation of phase at its unity crossing. Thanks to that it has 60dB phase margin, and I guess 20dB gain margin. It is the better of the two. But it rolls off from less than 10Hz (probably 2 or 3 Hz). The gain bandwidth and slew rate using The Art of Electronics formula says it hasn't much in the way of emitter degeneration, and the noise spec says it probably hasn't any at all. The slew rate calculates as 16.5V/uS but it shows 20V/uS suggesting "forced slew rate".

We tried both devices some years ago and found them to be highly signatured, which looking at the data looks about right for "hi-fi" (as in not high fidelity). But I'm sure my life would be much easier just to go along with the crowd.


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 11 Mar 2019 at 9:46pm
...how to read bode plots? Well, er, no.. [Me thinks I need to get this The Art of Electronics quick!] 

 ...easier just to go along with the crowd. Easier?!! You? Nope. Can't figure why you'd want to when you've figured out the circle the rest keep going around in! And it won't suit you. 

ThankYou! so much for putting up just the necessary comparisons for when looking for likely devices for RIAA duties. The world is fond of ones like its own. And that conform to its doings. I appreciate that you are not like that. You also have a wonderful patience to put up with numb-skulls like me who can only try and keep up but miss out on having the intelligence to do so. 
 You also touched upon something I have just come to realize: How the designers/committee board relegate what case they will release a device in... PDIP or SMD only + now their mobile phone miniatures! I would gladly have 50-odd BC184's to solder in than one of those things! 
  The semantics have dug their own grave. But they forget that people exist who will tell the king he's naked and an idiot and won't want to listen to something that isn't High Fidelity. Alas, they have the kind of money that these pieces of equipment require for ownership. So, getting back to DIY,... Have you thought of doing another Kit like the Genera? Still a RIAA amp but maybe a level up? Has 'nothing new' come about in the world of renewed interest in "playing records" again but this time, like we've never heard before? An easy tell that CD just can't replace the vinyl we love?!  I don't particularly like it when some say that vinyl just can't produce the frequency response that digital can as I'm not ready to get one of those DAC thingy's... Don't see a need... 
Meanwhile, I need to get myself another book: The Art of [getting things right this time!] 
     


Posted By: Graham Slee
Date Posted: 12 Mar 2019 at 1:54am
Can I answer one of your questions by asking if your Genera kit has arrived yet? When built and "run-in" I think it might approach the suggested nirvana. Not saying it will be like you've never heard before, but maybe an improvement on what you have heard?

Although the circuitry I like looks simple, and is simple most of the time, doesn't mean folk can build any close-enough values round an op-amp and rely on the op-amp to give them staggering results. And I'm glad you're seeing past the smoke and mirrors. Just need a few thousand more like you (it won't happen).

Both DIY and industry are full of opinions aimed at pulling in the crowds. It's how money is made. We all need to make a living, but some are "more equal" than others. Mostly I see people being pulled in by things I'd find very difficult to give a technical explanation of. This doesn't mean I'm right and they're wrong, but it might do.

Thank you for pointing me at Nelson Pass. I read http://www.firstwatt.com/pdf/art_dist_fdbk.pdf - http://www.firstwatt.com/pdf/art_dist_fdbk.pdf . Quite eloquently put, and I would have difficulty writing such a convincing piece. He is of course right with some of it.

He concludes saying: "By contrast, it appears that if you can make a single stage operate at .01% 2nd harmonic with a single tone without feedback, you could also achieve the 0.1% peak in the complex IM test. I like to think the latter would sound better."

"If you can" being the operative words. If I could make a single stage without NFB do 0.01% it would be a miracle. Obviously most of this  is written with a view of selling his class-A amplifiers (a guy has to make a living after all).

So let's take a quick look at the figures I last measured from my class-AB 1970s Design Indulgence, a simple amplifier with negative feedback...

Overall THD. Not just 2nd harmonic, but all its others summed by the 1 kHz THD test: 0.015%. IM: 0.05%.

Listening however exposed other problems and the test measurements at 10 kHz and 20 kHz were not out of the ordinary. At high frequencies there are more non-linearities, and can be around 0.1% THD which is higher than the 1 kHz most quote, and that's because open loop gain is falling as frequency increases.

Sacrificing some phase and gain margin to obtain 6dB more negative feedback (yes more NFB) made it sound much better. But then again will it still be better once the brand new dominant pole ceramic capacitors "bed in" after a few days constantly on? And how many lectures discuss constantly on?

I guess I'm an objectivist subjectivist.



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 12 Mar 2019 at 11:04pm
"I guess I'm an objectivist subjectivist." Perfect!! ClapWink 

Just quickly, no it hasn't arrived yet but there IS a suggested delivery of this Friday.. (yet they [UPS] say it's arrived for customs in Koeln, Germany) I have been told by the post here to disregard a lot of their tracking messages... Confused it'll arrive when it gets here! I'll let you know as soon as it does! Thanks! 
After getting used to Frequency Response graphs - I would never buy a speaker unless I could check out its response first! so I am thinking, once I get the hang of the Bode Plots and what to look for, the rest will come easy. 
I'll get back to the rest of this later... Really appreciate your Help and Guidance! 
DogBox [Steve 


Posted By: DogBox
Date Posted: 15 Mar 2019 at 12:50am
Well, today is the day when I should receive my Genera! I am so very tempted to update my amplifier system to separate Pre and Power units. I also was fortunate enough to get myself a Class A amplifier [also in kit form - going to be busy! yes!] that has rated distortion levels with lots of zero's after the decimal point until the first numeral! Although integrated, I think it has only one set of RCA inputs. 
 If the Genera is as good as it can get, I notice that the use of Carbon resistors are among the Metal Film.. I would have thought to try and "select" all components as close to the schematic as possible?  Are there places on the circuit board where Metal Film resistors are not a good idea because of their makeup?  
 I was also wondering if you could transfer a single op-amp to circuit board to be then able to alter it to your specific needs IN a project build?? too much trouble? Can't alter any further what makes up a Packaged Op-Amp design to specialize it to do what You want it to do? 
 I would have thought the Designers of op-amps would have to cater to a 'large market' to have their product viable to do many things... Why can't you have a Op-Amp only good for One application and One design parameter? The Best Chip you could possibly make for a RIAA pre-amp that wouldn't be any good for any other purpose because of its makeup? 
No, I don't know enough about electronics to answer my question, so maybe the clever, illustrius, objectivist's may. If they can design a chip to do a multitude of things - why can't they design one to DO only One thing, really good! 
Probably because life wasn't meant to be easy...I know... but.. I had nearly forgotten about an article that really made me laugh, because of the fun involved and the building of speakers of which is my main passion. Nelson Pass, with some help, made these speakers called "El Pipe-o" from 2002 that I first read in Audio Express magazine [also found here at the 2002 date   http://www.firstwatt.com/articles.html - http://www.firstwatt.com/articles.html ] I'm all over things like this! Absurd? yeah, so? 
C'mon mr delivery man...  


Posted By: Graham Slee
Date Posted: 15 Mar 2019 at 8:15am
All metal film here: https://www.hifisystemcomponents.com/forum/phono-preamp-project_topic745_post6492.html#6492

Should be all metal film in the parts kit too, unless a substitution. I have a CF assortment I bought years ago and used some (when I couldn't find an MF) when developing the Genera as can be seen in earlier photos.

The people who pack the kits (to order by the way) are the same people who build everything I do: John and Leo, so will have hopefully got it right. Wink I don't because my eyesight is worse than theirs...WinkWink

Interesting you have a "zero distortion" class-A one-input integrated amp kit. I'd try the Genera with what you already have. The music will keep you focussed as you ponder all those transistors.

Single op-amps often have offset-null pins, which are "inputs", and using the right pin you can tailor the response to taste. For example you can put a 10 pF cap between pin 6 and 5 on a TLO-71 and half its open loop bandwidth.

If you know how to bias it, both inputs can be tied together and AC grounded, and the offset-nulls then become (low impedance) inputs. AC ground one of them and you have a single sided op-amp. If you use pin 5 as input you can make a virtual earth (inverting amp).

Why you'd do that for audio calls sanity into question, but such techniques get used with video op-amps (for video use of course).


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 15 Mar 2019 at 10:58am
Well, "they" reckon it's THE quietist kit amp built! https://www.altronics.com.au/p/k5125-20w-class-a-amplifier-full-kit/ I have done a few of their Projects, learned a little bit here and there... With a decent [I like it! Goot RX-711 Soldering Station + extra tips for fine stuff] makes soldering a pleasurable past-time. I'll have to wait a bit longer as the UPS didn't come through with their "Expect it tomorrow" email they sent yesterday.. I hate 'having' to stay home all day to sign for what they say IS coming... and it doesn't. Unhappy Ah well, not the first time and won't be the last.. Also invested in a new [second hand but great cond!] Amp from Rotel.. a big one. Should be better than my Integrated with Tuner big Yamaha. Back to having separates [pre and power]. I am sure that when my two books get here and I start to soak up some things, my queries may be more interesting... at least! Well, here's hoping!  https://www.altronics.com.au/p/k5513-preamp-riaa-shortform-kit/ another Silicon Chip magazine project I have done and am "sure" it could be given some reworking [nothing too drastic] to really shine! Interesting way to use op-amps... http://diyaudioprojects.com/Chip/Phono-Preamp-Kit/  I am keen to hear what You think of this design, Graham.?? 
 You mention above about biasing an op-amp..! Could you Please expand upon this or point me to somewhere you may have already done so..? Greatly appreciated! Thumbs UpCool  


Posted By: Graham Slee
Date Posted: 15 Mar 2019 at 8:03pm
See page 6.184 http://www.miedema.dyndns.org/co/2018/Op_Amp_Applications_Handbook-Walt-Jung_2005.pdf - http://www.miedema.dyndns.org/co/2018/Op_Amp_Applications_Handbook-Walt-Jung_2005.pdf


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Fatmangolf
Date Posted: 17 Mar 2019 at 6:51pm
Thank you very much for that link Graham. I read that section and more, safely saved for future learning.



-------------
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: DogBox
Date Posted: 18 Mar 2019 at 12:35am
Fatmangolf said: I read that section and more, safely saved for future learning.

And I agree entirely! Wow! What a book! I hope they made it a little larger print than when you print some pages off for study later...talk about "the fine print"! I suppose they can pack more in, though.. 
 Monday's aren't bad when they deliver your parcel that they should've on Friday... Oh Dear, what a Friday THAT turned out to be.. Didn't get to find out the tragedy until about 5pm.. My heart goes out to the many people affected by the horrendous acts of one man(?). Senseless loss of precious life... so sad.   
 Now I can go and unpack and study my little kit! I was going to try out some new Kester "44" Rosin Core [i'm a Multicore type after it's what my dad used in the shop and I got used to it..?] Always on the lookout for some nice wetting/finish solder! You want to do the job Properly! after all!! Wink  No excuse not to have good solder joints. Lessen's problems later on.. 
Now, I wonder where those Book's I ordered are...? 
Getting back to that [also individual Section download from: https://www.analog.com/en/education/education-library/op-amp-applications-handbook.html] where the "constant velocity cutting head" is at the very core of the difficulty of extracting from those information-full-grooves "either" exactly what what put there OR Deciphering what was put there INTO what we want to hear when we play our records. Is it just a case of "reverse technology" to get everything from the groove that we put there? To look at it.. it's not very "High Tech" is it!? So, why haven't we been able to "get it" High Tech? Can't we initiate technology we have to do this in a better way? We are only dressing up the horse and cart we have been using for ages. The mechanical analog way has to be preserved but, can't we update it? Somehow? 
Seems like a place to start...    



Posted By: DogBox
Date Posted: 18 Mar 2019 at 2:38am
Hey Graham, you've seen this before..? surely... I found this when looking for guitar stomp box chips I could try...  https://www.analog.com/media/en/technical-documentation/data-sheets/lt1115fa.pdf - https://www.analog.com/media/en/technical-documentation/data-sheets/lt1115fa.pdf  its just that "this" particular one had my other love included - HiFi ! 
I'll get back to my Kit now!... See! Kit building is theraputic! Thanks Doc! 
Steve. 


Posted By: Graham Slee
Date Posted: 18 Mar 2019 at 8:11am
Steve, I'm sure all these alleged hi-fi buffs think I'm just a dim new kid on the block, or their impression of a thick Yorkshireman...

Yes, seen it. I don't know if LT were pandering to the hi-fi loons or if they invented the idea and the loons followed, but if you want a class-A (such an over abused description, yawn) then make one, and don't screw-up an already messed-up class B stage, by trying to defeat it in such a techy way.

Yes, Jung said you need a buffer to drive the EQ, but I think he meant a stable one. The excuse for the 499 ohm resistor will be to preserve the Neumman curve, which was news to Neumman...

I tried describing it as something similar but stood corrected a long time ago. Actually the padding resistor guards against instability, so why bother with the buffer? I think most are obsolete by now.

I think all the pretence about alleged hi-fi techniques ought to be exposed for the myth it all is. Just model-in every single parasitic there really is to any circuit and see the absolute garbage that comes out.

What works is what some poor sod slaved over for months or years until he found a sticking plaster large enough to cover the imperfections his work revealed, and luckily it sounded good enough to save his bacon.

All the rest is people living in dreamland. Just my opinion of course. Wink



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 24 Mar 2019 at 1:43am
Graham said: "Steve, I'm sure all these alleged hi-fi buffs think I'm just a dim new kid on the block,.." 

Well Graham, I am not concerned with what ANY "alleged hi-fi buff" says...however, I am very interested in your opinion of circuits like that ONLY because I feel I can learn something from your answer about them. I'm sorry if I give the persona of someone trying to insult you because I do NOT wish to do that at all. Please don't feel annoyed with me and my ignorance... I am just trying to learn to recognize the different aspects of RIAA design and to learn if possible the "right" way to do it. Clap 
So, I have come to you, to build one of your very successful designs and learn what I can from it. I am sure that when you put the Genera into a kit form, that you had to "do things a certain way" because it was a Kit that you had to rely on someone you don't know to put together 'properly'! Such that they couldn't 'make' any mistakes. Now, what things did you have to "change" because you couldn't have any control over how well your Kit was put together? I think I remember reading that the "finding the exact resistances" wasn't necessary... but, what CAN we do to make it the BEST it could get! This is my next question! Like, for instance, the cap over C9... Things like these and "why" you would do that..? My Art of Electronics should be here early this week, so I am looking forward to that! Maybe there is a chapter I should be reading First that may not be Ch.1??  I appreciate your putting up with idiots like me that "may eventually" get to know something useful! ThankYou! 
Kind Regards,
DogBox 


Posted By: Graham Slee
Date Posted: 24 Mar 2019 at 7:33am
OK, if you're here to learn but I once remember during a phone call being asked if I'd like to borrow his son's college books on op-amps. He said it might help me...

I was very polite... I suppose not being an electronics celeb, people might think that way.

I am not into hi-fi snake oil, but will say I used Elna ROD's in the past. Quite effective, but now banned being of an hazardous chemical nature. All components have characteristics, but I'm wise enough to avoid the opportunists.

Why "I would do that"? All I am actually doing is making a particular circuit work as well as can be expected. Making things do the best it could get might mean going to extremes in component value selection: 103.678 pF might theoretically do a better job than 100 pF for example, but all components have parasitics, and there are also manufacturing tolerances. Can the difference be heard? No is the usual answer. Can the difference be measured? Again I think the answer will be no unless it's some precision filter.

High end hi-fi is full of opinions and I know of some who are unstable enough to use violence in forcing their opinions. I think we can do without that? I remember one particular character doing the rounds of the forums telling everybody how bad the Solo headphone amplifier sounded. He later admitted he'd never heard one, but was just supporting his favourite brand.

And as for bypassing C9: I tried to explain what bypassing does in an earlier reply?


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 07 Apr 2019 at 12:33am
C9: I will get to try that now I have my "very own" Genera Phono Pre! Took your advice and put the highest voltage-to-size that would fit side-by-side and it exceeded my expectations for something I actually put together. I usually go by "if the ON led lights up - i've done something right!???" It has turned my Phono playing into "something else!" Very nice indeed! So, I got back to some reading and following along and I must be learning something because :  http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1965/Transistor%20High%20Quality%20Audio%20Amplifier.pdf - http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1965/Transistor%20High%20Quality%20Audio%20Amplifier.pdf has something VERY WRONG in it's explanation. On page 4. he starts to explain the workings of the schematic (Fig. 2) under the sub-heading: Revised Preamplifier. in the second paragraph which starts: "Equilisation is again performed by feedback.." and then makes connections referring to Fig. 2 that don't make sense! How is the "collector of Vt2 going to the emitter of Vt1...???" I even googled the symbol of a transistor to confirm my long held knowledge of some years back! It's things like THIS that "do my head in!" as I am really trying to make sense of all this and some bloke with a * MA after his name spruiks absolute bunk! Maybe I should get out my prototype board and make up his "amplifier" per schematic and see if it actually works..?? That much does look ok!  but I think i'll stick with Graham's explanations, thanks all the same. 
 As far as C9, all I could find [pretty quickly] was "see what you think - after it settles down for a while.." I researched 'By-Passing' but have forgotten [like so much these days] what it was I found out - which tells me it wasn't too profound... 
Anyone else give it a try? 

DogBox   


Posted By: Graham Slee
Date Posted: 07 Apr 2019 at 9:49am
Follow C5 to the right of VT2 collector via any of the EQ networks selected by S1b to the end of C4 which connects to Vt1 emitter.


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 07 Apr 2019 at 11:55am
Yes, I take it back. Didn't consider it could make its way via that route. Embarrassed Unhappy One day... (hopefully!) 
Maybe the Art of Electronics will knock a bit of sense into my head - if I can swing it right...! [pretty heavy!] Clown


Posted By: Graham Slee
Date Posted: 07 Apr 2019 at 5:00pm
As an old tutor used to say to me, when it gets too heavy, simplify! It got me through a year of mathematical modelling. Another clue he used to give me is "from what we know", but that is dangerous here because I'm guessing you've been reading in the wrong places. In fact I will go as far as saying you have been - this is obvious to me - I'm just trying to help.


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 08 Apr 2019 at 7:27am
Originally posted by Graham Slee Graham Slee wrote:

In fact I will go as far as saying you have been - this is obvious to me - I'm just trying to help.

Embarrassed ..Is it 'that' obvious? You are helping. ThankYou! for wanting to. I would 'really' love to get my head around "the nitty gritty" of it all. I've been trying to for quite a while and sometimes it does start to make sense when - then it doesn't. Maybe it never will. I do get a lot of enjoyment out of putting things like 'kits' together and getting things in the right places.. and thinking 'why' they get "put there!" I'll continue reading and trying to make sense of it all as listen to my records of Pink Floyd and Jimi Hendrix and Zero 7... that now sound better than I have ever heard them before! 
 Must be doing 'something' right..Shocked 

DogBox 


Posted By: Graham Slee
Date Posted: 08 Apr 2019 at 8:03am
Isn't it amazing how a reasonably-well thought out circuit can sound using nothing more than "industrial" components? Wink

Incline toward the engineering and away from the bluster and you won't go far wrong.



-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 21 May 2019 at 3:30am
Ok, "away from the bluster" and on with the show! 

Now having graduated the Genera test using the biggest capacitors I could fit on the PCB; all turned out pretty swell! My music sounds much better but now something has happened to my ears OR my stereo.. Doesn't have that "air" it had before... Because of better [proper!] interconnects..?? Am I getting 'used to it'..?? 
  Well, going to try a LOMC cartridge. I have an Ortofon MC 15 Super III and am getting a Benz Ace - the low output Red version (0.4mV), the Ortofon 0.34mV. Looks like I'll have to give the Genera some Help OR also get a SUT or something appropriate to let these cartridges do their thing, in the Quest for an 'upgrade' further up the ladder of bliss! 
 Could someone offer some advice on the best way to go? Without having to shell out even 'more' money I haven't got..? 

And i'm not too clever electronically so the K.I.S.S. principle applies for me... Ask Graham, he'll tell you! 

DogBox   


Posted By: tg [RIP]
Date Posted: 21 May 2019 at 4:03am
https://www.hifisystemcomponents.com/forum/phono-preamp-pt2-mc_topic1459_page9.html - https://www.hifisystemcomponents.com/forum/phono-preamp-pt2-mc_topic1459_page9.html

Schematic at the bottom of the page looks like what you are asking for here.


-------------
Tony G


Posted By: Graham Slee
Date Posted: 21 May 2019 at 4:15am
"Truly great audio components never happen by accident: if a given designer/company produces one exceptionally great component, it doesn’t take any exceptional leap of faith to suspect that they know what they’re doing" - from an upcoming review.

So, in your wisdom you've altered the design - you've "graduated it".

Now asking for help to make things better elsewhere?

Without a reference (which you had) you will end up going around in ever decreasing circles, never being able to get what you want.

Added to that I gave away a great (but simple) way of enabling you to use an MC cartridge with your Genera, but it would seem you've chosen to ignore that.

I feel you're not going to get any useful answers because it can be seen that you're willing to ignore expert advice, or are perhaps confused, and perhaps thinking the fountain of knowledge comes from amateur magazines/all over the net? There is a reason for particular circuits appearing in amateur magazines and internet, which might well be touted as the best thing since..., but they're there because they don't make it at a professional level.

Nobody gives away a proper design, except me perhaps.

-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 21 May 2019 at 4:55am
Yes Graham, you're right again. Something makes me chase my tail and frustration could well be "it" because I simply don't know enough about electronics. I just have to face that I never will. 

You have been extremely Kind and Very Generous! Please do not think I don't appreciate it!.. even if I am not worthy of it. You're a terrific bloke! 

I didn't ignore your diagram - I just didn't know it was there... Sorry. 

I have access to the fountain of knowledge as I actually purchased the Art of electronics you talked about and if it wasn't for Professional people like yourself - the magazines wouldn't have anything to fill their pages. Let's hope they don't go to china to look for new material... :o 

I hang my head in shame once again. 

Steve


Posted By: Graham Slee
Date Posted: 21 May 2019 at 7:08am
No, you shouldn't hang your head in shame. This I hope is a learning experience, and that is what I want to share with those who appreciate it.

I can understand, and even feel your frustration, because I was there, albeit 45 years or so ago.

And what bugs me about the magazines is there is no enthusiasm to teach anymore, because I'll tell you I'd rather get the understanding that can be gleaned from such as Ray Marston (Nuts and Volts) than trudge through the Art of Electronics for a more lengthy explanation. Yes, sometimes an old-hand can forget.


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: Graham Slee
Date Posted: 21 May 2019 at 1:30pm
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_1 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_1
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_2 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_2
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_3 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_3
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_4 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_4
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_5 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_5
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_6 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_6
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_7 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_7
https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_8 - https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_8


-------------
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps


Posted By: DogBox
Date Posted: 21 May 2019 at 1:49pm
Yep, that should keep me out of your hair for a good while. Lets hope something might sink in... 
I have a few days before the MJE243G arrives from Farnell (Element14 in Oz) ...bye.. 
Thanks for the links 


Posted By: BAK
Date Posted: 21 May 2019 at 2:35pm
I found "Nuts and Volts" to be a great resource for designing all kinds of circuits. We had a regular subscription at the medical electronics design and repair shop in the 1990's.

-------------
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!


Posted By: DogBox
Date Posted: 23 May 2019 at 7:28am
Hi Bruce,
And ThankYou! I have been trying to sink my teeth into it and it reminds me of a magazine here in Australia - Silicon Chip, which have also put out a lot of Kits. Where I have gotten a lot of my circuit board soldering skills and component placement knowledge from. Doesn't mean that my electronic knowledge is anything though. But I keep on trying as its also just about all I can do these days because of my physical health being zilch. I can remember doing reasonably well for a while when I started studying to get my Novice Radio Licence and life sort of got in the way and I didn't get to continue it. Funny, I could understand valve circuits easier than transistor. :o I am not going to ask Graham if he ever thought about doing a Valve Phono Pre...! I'd get shot! I bet Medical Electronics was a lot of fun! An amazing amount of electronics has been able to help the medical profession. I bet you miss it..?? 
Regards, Steve. 
<PS> So good to have the Forum back up again...Yay!!! 


Posted By: ICL1P
Date Posted: 23 May 2019 at 8:08am
Originally posted by DogBox DogBox wrote:

I am not going to ask Graham if he ever thought about doing a Valve Phono Pre...!
He has; you’ll find the forum thread somewhere.

-------------
Ifor
=====
Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.


Posted By: DogBox
Date Posted: 26 May 2019 at 3:30am
Originally posted by ICL1P ICL1P wrote:

[/QUO
He has; you’ll find.....[/QUOTE] 

Really!!?? Well I never..! 
I'll have to do a search on that one. Hopefully I can follow along... Thanks ICL1P!! Thumbs Up


Posted By: ICL1P
Date Posted: 26 May 2019 at 9:22am
Originally posted by DogBox DogBox wrote:


Really!!?? Well I never..! 
I'll have to do a search on that one. Hopefully I can follow along... Thanks ICL1P!! Thumbs Up

https://www.hifisystemcomponents.com/forum/valves-seen-on-graham-slees-desk_topic2792_page1.html?KW=Valve



-------------
Ifor
=====
Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair.


Posted By: DogBox
Date Posted: 26 May 2019 at 11:58am
Quote https://www.hifisystemcomponents.com/forum/valves-seen-on-graham-slees-desk_topic2792_page1.html?KW=Valve

Clap Thanks ICL1P!! 14 Pages! Should I stay Excited...?!! I hope so.. 

DogBox



Print Page | Close Window

Forum Software by Web Wiz Forums® version 12.01 - http://www.webwizforums.com
Copyright ©2001-2018 Web Wiz Ltd. - https://www.webwiz.net